The currently available techniques for determining the movement of fluid and proppant (sand) into or through a subsurface formation rely on secondary measurement techniques such as Micro Seismic or modeling, neither of which can show where the fluid or proppant has been injected, and only infer the location. Micro Seismic Monitoring (“MSM”) and is typified by U.S. Pat. No. 7,872,944 and is incorporated herein by reference.
“System and method for detecting a fracture in a rock formation using an electromagnetic source,” U.S. Pat. Pub. 20140239956, is incorporated herein by reference and is an example of an attempt define the process through modeling but does not define how such a system would operate in the real world and makes several errors of omission as described in “Coherent transmit/receive bi-static electromagnetic geophysical tomography system,” U.S. patent application Ser. No. 14/491,113, filed Sep. 19, 2014, which is incorporated herein by reference.
The current state of the art in Hydraulic Fracturing (fracing) bases a fracing program around experience gained from methods used previously, modeling the expected stress profile of the area and many other modeled factors. This results in a recipe book approach to fracturing that is variously successful. An indication of the effectiveness of this technique is the statistic that fracing is only about 40-50% successful in producing usable reserves.
The current state of the art for flow back operation is not to monitor them at all with techniques that might reveal the subsurface activity. More typically the monitoring of the flow back operation involves reviewing pressure, temperature and flow rate data and the quality of the fluid arriving at the well head.
The current state of the art for Enhanced Oil Recovery (EOR) is to monitor the process through various techniques that try to understand which of the Hydraulic Fracture (fracs) stages were successful and are producing in order to customize the fluid or gas injection locations and rate.
The current state of the art in long term monitoring of known reserves is to use modeling, in-hole measurements of temperature and pressure and surface readings of pressure, flow and temperature.